In recent years, a considerable amount of optical fiber has been added to the global communications infrastructure. While optical fiber provides a great deal more bandwidth than a comparable conventional wire cable, continuing increases in the available bandwidth are necessary. This is driven in part by the exponential growth in IP traffic.
In response to the increased demand for bandwidth, communications carriers and equipment vendors are researching means for simplifying the global communications infrastructure. One of the areas of research relates to means for bringing the IP and SONET/SDH transport layers closer to the common optical transport layer and efficiently supporting the exponential bandwidth demands. Solutions in this area are anticipated to be very cost-effective.
Currently available switching products are usually based on 2n electrical switching fabric. One problem with these products is the scalability of the systems. Although the bandwidth and speed of these systems continues to increase, they are not expected to be able to meet the bandwidth demands of the future. Even if these demands could be met, it is anticipated that the many interconnects and fabric elements required in a terabit electrical switching fabric would present an operational nightmare in terms of the provisioning and management of the system.
Another problem with these systems is that, the per port fabric bandwidth is at least two orders of magnitude slower than the photonic switches. Electrical fabrics can currently handle a bandwidth of about 2.5 Gbps, while photonic switching elements can switch over 40-nm of optical bandwidth with multiple parallel optical frequencies, each with a modulation rate exceeding 10 Gbps, resulting in per port fabric bandwidths exceeding 450 Gbps. Thus, the throughput of an electrical switching fabric will be substantially lower than a comparable photonic switching fabric. Furthermore, optical fabrics can be reconfigured on the order of nanoseconds.
A related problem is that, even though photonic switches have the potential to operate at much higher data rates than electrical switches, it is very difficult to implement a photonic switch at these data rates. As a result of these difficulties, photonic switching systems in the prior art do not switch data at the packet level. Instead, connections are maintained from a particular set of ingress ports to a particular set of egress ports. These connections remain in place for long periods of time (e.g., hours or even days). It should be noted that, in order to implement switching at the packet level using prior art systems and methods, the routing of data from the ingress ports of the edges to the switch core and then out through the egress ports of the edges would have required individual optical fibers for each of the ports, thereby limiting the scalability of the switching system.